/**
* Copyright 2009 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.waveprotocol.wave.model.wave.undo;
import org.waveprotocol.wave.model.operation.wave.AddParticipant;
import org.waveprotocol.wave.model.operation.wave.NoOp;
import org.waveprotocol.wave.model.operation.wave.RemoveParticipant;
import org.waveprotocol.wave.model.operation.wave.VersionUpdateOp;
import org.waveprotocol.wave.model.operation.wave.WaveletBlipOperation;
import org.waveprotocol.wave.model.operation.wave.WaveletOperation;
/**
* Utility methods.
*
*/
final class OpUtils {
private OpUtils() {
}
/**
* Returns true iff the wavelet operation is considered a no-op as far as undo
* is concerned.
*
* @param op
*/
static boolean isNoop(WaveletOperation op) {
if (op instanceof VersionUpdateOp || op instanceof NoOp) {
return true;
} else if (op instanceof AddParticipant || op instanceof RemoveParticipant
|| op instanceof WaveletBlipOperation) {
return false;
} else {
// This happens when the op parameter is a non-core subclass of
// WaveletOperation, not supported by wave.
throw new RuntimeException("Unhandled op:" + op.getClass());
}
}
}